Being a guy I know firsthand that sometimes what guys need is for girls to spell out their feelings in detail for us to understand. I'm blessed (cursed?) with a slightly better/more feminine sense of empathy than most of my kind, but it is still important to understand that communication is the most important key to maintaining a relationship.
Don't be afraid to tell him in detail what it is you're feeling; don't think he'll leave you if you do, because probably the opposite will happen. Guys don't have the innate emotional sensitivity that girls do, which is why you rarely ever see guys comforting each other as girls do for example. But giving him that extra little bit of insight to your heart will probably help him feel even closer to you, which if you both love each other can only strengthen your relationship.
As far as your parents go, I would advise you to be careful. If he's in college now and you rarely get to see each other in person, then keep your meetings to being every once in a while and things that friends would go out and do, so you can minimize suspicion. Once you're 18 and/or out of the house and in college (if it lasts that long, and you have my best wishes that it does :) you'll have more control over your own life and your parents' expectations of you won't be as much of a problem.
And trust me, I understand how that can be; my last year of high school I met a freshman girl who was Asian, and we almost became a couple but she broke it off because her parents wouldn't approve of it. Things went downhill from there, and she stopped speaking to me :( But I do sympathize with your situation.
But I digress. Like I said, don't be afraid to come out and tell him what's wrong; don't assume that he should be able to tell, because quite honestly guys just can't do that sometimes, so we need to be told. Don't be more upset or act annoyed because you have to spell it out for him, but be loving and understanding and be detailed about how it is you feel. And if you both talk about what it is that upsets you then it'll be easier to work things out to keep that from happening and keep you from having to argue as much.
Best of luck :)